Gun



Patented Aug. l0, 1937 UNITED STATI-:s

PATENT OFFICE 8 Claims.

(Granted under the act of March 3, 1883, as

amended April 30,

Ihe invention described herein may be manufactured and used by or forthe Government; for governmental purposes, without the payment to me ofany royalty thereon.

This invention relates to a gun and to a method of permanently reshapinga projectile passing through the gun, and is a continuation in part ofabandoned application Serial No. 696,207 led November 1, 1933.

From the standpoint of interior ballistics it is desirable to have abullet which has little mass but great cross-sectional area andconsequently low sectional density in order to give the powder gases asufficient area upon which to push. From the standpoint of exteriorballistics it is most desirable to have a bullet of the smallestcrosssectional area with the greatest sectional den sity.

The purpose of this invention is to provide a gun barrel which iscapable of permanently reshaping a specially formed bullet during itspassage through the bore of the gun whereby the bullet may conform tothe requirements of interior and exterior ballistlcs. As a consequencehigher muzzle velocities may be obtained with the same chamber pressuresnow employed in conventional weapons, or conversely, the same muzzlevelocity may be obtained with lower developed pressures.

More specifically the invention consists in providing a gun barrel withrifling which not only serves to impart rotation to the bullet but whichacts as a forming die to reshape a part of the bullet and reduce itscross-sectional area.

To these and other ends, the invention consists in the construction,arrangement and combination of elements described hereinafter andpointed out in the claims forming a part of this specification.

A practical embodiment of the invention is illustrated in theaccompanying drawing, wherein:

Fig. 1 ls a longitudinal sectional view of a gun barrel constructed inaccordance with the inven- 45 121011.

Figs. 2, 3, 4, and 5 are sectional views on the respective lines of Fig.1.

Fig. 6 is a longitudinal sectional view of a bullet before passingthrough the gun barrel.

Fig. 7 is a rear end view of Fig. 6.

Fig. 8 is a view in side elevation of the bullet after passing throughthe barrel.

Fig. 9 is a rear end view of Fig. 8.

Referring to Figs. 1 to 5, the gun barrel 5 has a 55 bore in which lands6 are gradually widened from breech to muzzle and at the same timegradually converged towards the axis of bore at the muzzle with theresult that the grooves 'l are gradually narrowed Aand deepened towardsthe muzzle. The twist of the rifling as shown is only about one-half ofa turn in the entire length of the barrel, the barrel being of theconventional length of 24 inches for .30 caliber ammunition, or 80calibers in length.

A preferred form of bullet for use with the l gun barrel is shown inFigs. 6 to 9 and consists of a body 8 and an integral enlarged hollowbase 9 constituting a cup-shaped tail approximately one-half as long asthe body. The diameter of the rear end of the base 9 is approximatelytwice the maximum diameter of the body.

The base 9 is formed with a hemi-spherical cavity l0 which is incommunication with a cavity Il provided axially in the rear portion ofthe body. The wall of the base is of a gradually decreasing thicknessfrom its front to its rear end.

The base 9 is composed of a metal which is deformable and which may bepermanently reshaped. The gun barrel constitutes a forming die whichacts on the base to permanently reshape it providing ns I2 as shown inFigs. 8 and 9 and reducing the cross-sectional area of the base. Duringthe travel of the bullet through the greater part of the gun barrel itsbody 8 is out of contact with the bore. At the muzzle of the barrel thelands 6 are preferably dimensioned to slightly contact the body 8 andthereby give it lateral stability.

Approximate calculations of the interior ballistlcs of the bullet madein comparison with a conventional .30 caliber bullet are as follows;assuming bullets of the same weight and the same developed pressures.Where the diameter of the base 9 is twice that of the body 8, then theacceleration of the bullet will be four times that of the conventional.30 caliber bullet. Approximately the same amount of energy is consumedin reshaping the base 6 as is used in giving rotational movement to the.30 caliber bullet.

The particular form into which the base 6 is reshaped will depend on thenature and character of the lands and grooves of the gun barrel. Whilefour lands and grooves have been shown it is obvious that the number maybe varied and that they may be arranged to produce diierent shapes ofthe fins I2. The ns may be formed with a curve so that in ight thebullet may literally screw itself through the air.

By reference to Figs. 2 to 5 it will be noted that 55 the diametraldistance between the lands at the muzzle is approximately one-half themaximum diameter of bore and also approximately equal to the depth of agroove. -The total convergence 5 for each land is approximately equal toone-fourth the maximum diameter of bore.

While the invention finds its most practical application for small armsthe principles set forth are equally applicable to all classes ofweapons ,l0 irrespective of their caliber.

I claim:

l. A gun barrel having a bore with lands and grooves, the lands beinggradually widened from breech to muzzle and gradually converging towardsthe axis of bore at the muzzle with a total convergence for each landapproximately equal to one-fourth the maximum diameter of bore, thegrooves being gradually narrowed and deepened towards the muzzle whileretaining the maximum diameter of bore, and the lands and grooves havinga twist of approximately one-fourth to onehalf of a turn in a barrel ofapproximately eighty calibers length.

2. A gun barrel having a bore with lands and .25 grooves, the landsbeing gradually widened from breech to muzzle and gradually convergingtowards the axis of bore at the muzzle, the grooves being graduallynarrowed and deepened towards the muzzle while retaining the maximumdiam- 30 eter of bore, and the lands and grooves having a twist ofapproximately one-fourth to one-half of a turn in a barrel ofapproximately eighty calibers length.

3. A gun'barrel having a bore with lands gradu- 35 ally widened frombreech to muzzle and gradually converging towards the axis of bore atthe muzzle with a total convergence for each land approximately equal toone-fourth the maximum diameter of bore, and the lands having a twist ofapproximately one-fourth to one-half of a turn in a barrel ofapproximately eighty calibers length.v

4. A gun barrel having a bore with lands gradually widened from breechto muzzle and gradually converging towards the axis of bore at themuzzle, and the lands having a twist of approximately one-fourth toone-half of a turn in a barrel of approximately eighty calibers length.

5. A gun barrel having a bore with lands gradually converging towardsthe axis of bore at the muzzle and with grooves having a constantdistance from the axis of bore and the lands having a twist ofapproximately one-fourth to one-half of a turn in a barrel approximatelyeighty calibers length.

6. A gun barrel having a bore with lands and grooves, the lands beinggradually widened from breech to muzzle and gradually converged towardsthe axis of bore at the muzzle, and grooves being resultingly narrowedand deepened towards the muzzle, and the diametral distance between thelands at the muzzle being approximately onehalf the maximum diameter ofbore.

7. A gun barrel having a bore with lands and grooves, the lands beinggradually widened from breech to muzzle and gradually converged towardsthe axis of bore at the muzzle, the grooves being resultingly narrowedand deepened towards the muzzle, and the diametral distance between thelands at the muzzle being approximately equal to the depth of a groove.

8. A gun barrel having a bore with lands gradually widened from breechto muzzle and gradually converging towards the axis of bore at themuzzle with a tctai convergence for each land approximateig7 equai toone-fourth the maximum diameter of bore.

WILEY T. MOORE.

